The present invention relates generally to pointing devices and, more particularly, to a pointing device having direct drive sensors for position sensing and a gear system for gear reduction in a force feedback mechanism of the pointing device.
One type of pointing devices incorporates a force feedback feature. Such devices are commonly used in an interactive system which typically displays a visual environment to a user on a display screen. The user can interact with the displayed environment to play a game through the use of a user manipulable object or user interface device, such as a joystick, joypad button controller, mouse, trackball, stylus and tablet, or the like. The interface device is connected to the computer system controlling the displayed environment. The computer updates the simulation or game in response to the user""s manipulation of the user manipulable object, and provides feedback to the user. Some interface devices produce tactile or force feedback to the user by providing physical sensations to the user. Typically, motors or other actuators are coupled to the user manipulable object and are controlled by the computer system. Position sensors monitor the position of the user manipulable object and provide the measurement data to the computer system, which processes the data. Based on the data, the computer system generates control signals for controlling the motors to produce feedback forces to the user manipulable object, thereby conveying physical sensations in addition to visual stimulation to the user.
Pointing devices such as joystick devices tend to have extensive linkages that include, for example, gimbals or other mounting components. Position measuring sensors are typically placed remotely from the user manipulable object such as a joystick handle where the movement is occurring. As a result, tolerances between the linkage components (for instance, the various parts of the gimbals and mounting structure for the sensors) reduce the precision of the position measuring system. This in turn diminishes the quality of the game play.
The present invention is directed to a position sensing apparatus for a user manipulable object in a pointing device such as a joystick. The position sensing apparatus employs sensors that are directly or essentially directly connected to the user manipulable object to reduce backlash, and are mounted in a way to substantially eliminate off-axis loading on the sensors. The reduction of backlash produces more accurate position measurements to enhance game play, while the elimination of off-axis loading protects the sensors from damage to the internal mechanism thereof.
In some embodiments, the pointing device incorporates a force feedback mechanism which includes a gear reduction system that utilizes an annular reduction gear portion for force transmission from the force feedback actuator to the user manipulable object of the pointing device. The annular reduction gear portion produces a greater gear reduction than a conventional gear in a given space and hence a smaller actuator can be used. The gear reduction system is configured to take up less space. As a result, the pointing device is compact and accurate, and can be produced economically.
In accordance with an aspect of the present invention, a force feedback mechanism comprises a user manipulable object, and an actuator for driving the user manipulable object in rotation around an axis. A gear system is coupled between the actuator and the user manipulable object. The gear system provides a gear reduction from the actuator to the user manipulable object. The gear system includes at least one annular gear portion which includes teeth on a concave side engaging teeth of a pinion for driving the annular gear portion.
In accordance with another aspect of the invention, a joystick device comprises a joystick. A first gimbal arm is coupled to the joystick, and includes a first annular gear portion having gear teeth on a concave side thereof. A first gear system is coupled with the first annular gear portion of the first gimbal arm. A first actuator is coupled with the first gear system for driving the joystick in rotation around a first axis. Rotation around the first axis typically produces front-back movement of the joystick. A second gimbal arm is coupled to the joystick, and includes a second annular gear portion having gear teeth on a concave side thereof. A second gear system is coupled with the second annular gear portion of the second gimbal arm. A second actuator is coupled with the second gear system for driving the joystick in rotation around a second axis. Rotation around the second axis typically produces left-right movement of the joystick.
In accordance with another aspect of the invention, a joystick device comprises a joystick having a joystick axis and being supported to rotate with respect to a first axis which is nonparallel with the joystick axis, and to rotate with respect to a second axis which is nonparallel with the joystick axis and the first axis. Rotation around the first axis typically produces front-back movement, and rotation around the second axis typically produces left-right movement, of the joystick.
A first sensor has a first sensor body coupled with a first sensor shaft. The first sensor shaft is substantially immovably connected to the joystick to move with the joystick. The first sensor shaft is rotatable relative to the first sensor body generally around the first axis. A first mounting mechanism is coupled to the first sensor body to permit the first sensor body to move with the first sensor shaft except in rotation around the first axis.
A second sensor has a second sensor body coupled with a second sensor shaft. The second sensor shaft is substantially immovably connected to the joystick to move with the joystick except the second sensor shaft is movable relative to the joystick in rotation around the joystick axis. The second sensor shaft is rotatable relative to the second sensor body generally around the second axis. A second mounting mechanism is coupled to the second sensor body to permit the second sensor body to move with the second sensor shaft except in rotation around the second axis.
In a specific embodiment, a boss is inserted into a slot in the joystick. The slot is configured to permit movement of the boss relative to the joystick substantially only in rotation around the joystick axis. The second sensor shaft is substantially immovably connected to the boss, so that the second sensor shaft is substantially immovably connected to the joystick to move with the joystick except in rotation around the joystick axis.